The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art.
An antenna system of a mobile communication base station that is currently widely used has a structure in which radiation elements vertically arranged for transmitting or receiving two polarized waves perpendicular to each other. It is necessary to adjust the tilt and azimuth or other factors of the antenna in order to align the polarization directions between the transmit and receive antennas or to improve transmission and reception performance.
In the past, to adjust the tilt and azimuth of an antenna, a mechanical method was mainly used involving a technician to climb up a tower and manually adjust the entire antenna. The mechanical method is not only dangerous, but also is disadvantageous with a difficulty to immediately tackle an emergency situation.
Recently, an electrical method has been employed in which a phase shifter is inserted into an antenna, and then the tilt and azimuth of the antenna are electrically adjusted. A method of electrically controlling an antenna is disclosed in Korean Patent Application Publication No. 10-2010-0122092.
The types of devices to control the antenna include: a remote electrical tilt unit (RET) to control the tilt of the antenna, a tower-mounted amplifier (TMA) to control the amplifier, a remote azimuth steering (RAS) unit to adjust the azimuth of the antenna, and an remote azimuth beamwidth (RAB) unit. There are various other antenna control devices such as an alignment sensor device (ASD), an antenna clock source (ACS), a geographic location sensor (GLS), a configurable power monitor (CPM), an antenna temperature sensor (ATS) and a remote antenna extension (RAE). As technology advances, new antenna control devices are being added. In this specification, the above-described antenna control devices are referred to as antenna line devices (hereinafter, “ALDs”).
In the current mobile communication environment, in which 2G, 3G and 4G (4th Generation Long Term Evolution) systems have been commercialized and 5G is being prepared for introduction, various communication service frequency bands coexist according to communication systems or operators and countries. In order to facilitate integrated management of the base stations and to reduce the operational cost of the base stations, a plurality of base stations is consolidated in many cases.
A base station system may be composed of a plurality of base stations conforming to different communication standards and antennas of the bands used by the respective base stations. In the base station system, service coverages may overlap and it is necessary to coordinate the antennas to minimize signal interference in regions where coverages can overlap each other. Attempts have been made to apply antenna control techniques to minimize signal interference and maximize network capacity in a base station system.
Conventional techniques related to a base station system are disclosed in Korean Patent Application Publication No. 10-2013-0070144 and Korean Patent Application Publication No. 10-2013-0087362.
FIG. 1 is a diagram of a conventional base station system.
The base station system includes a plurality of base transceiver stations (BTSs) and antennas used in the respective BTSs. The respective BTSs 111, 112 and 113 are connected to the antennas 141, 142 and 143 used by the BTSs on a one-to-one basis.
Each of the base stations 111, 112 and 113 is connected to each ALD 131, 132 133 via ports 121, 122 and 123. The ALDs 131, 132 and 133 control a corresponding one of the antennas 141, 142 and 143.
In the conventional antenna control methods disclosed in Korean Patent Application Publication No. 10-2013-0070144 and Korean Patent Application Publication No. 10-2013-0087362, each BTS directly controls an antenna connected thereto on a one-to-one basis. However, as communication systems become more complex, it has become necessary to flexibly set the antennas to be controlled by each BTS.